Oligoalanine-modified Pluronic-F127 nanocarriers for the delivery of curcumin with enhanced entrapment efficiency.

Curcumin is a naturally occurring compound that has been shown to have anti-oxidant, anti-inflammatory, and anti-carcinogenic activities. However, its pharmaceutical potential has been limited due to its low solubility in water. The use of amphiphilic nanocarriers is an attractive and simple method to solubilize curcumin. In this study, we modified Pluronic F-127 [poly(ethylene glycol)100-block-poly(propylene glycol)65-block-poly(ethylene glycol)100] (PF-127) with oligomers of alanine, an amino acid, to increase the drug entrapment efficiency of curcumin through core stabilization. Alanine-modified PF-127 exhibited lower critical micelle concentration and decreased molecular motion in both the hydrophilic and hydrophobic segments ((1)H NMR). Nanocarriers in the size range of 54.2-68.4 nm were observed. Entrapment efficiency of curcumin increased by at most 66% (from 25.3 to 91.3%) and the difference in solubility was clearly visualized by increased transparency of the nanocarrier solutions. Curcumin was released continuously up to 120 h from modified carriers, while drug release from unmodified carriers plateaued within 24 h. These modified nanocarriers exhibited no cytotoxicity and more efficiently delivered drugs to HeLa cells as confirmed by fluorescent microscopy. This study demonstrated that alanine modification of FDA-approved PF-127 affects copolymer nanoassembly and has a profound impact on curcumin loading and possibly on other hydrophobic drugs as well.